This project concerns the role of palmitoyl coenzyme A hydrolase and related acyl coenzyme A hydrolase(s) in the regulation of cellular metabolic processes, particularly in the regulation of lipid metabolism. The hydrolase(s) may provide an alternate fate for activated fatty acids, that is, deactivation by cleavage of the thioester bond, and thus serve to vary the intracellular concentrations of these lipids in response to the energy demands of the cell. The hydrolase activity of rat submaxillary gland will be measured under a variety of physiological, pharmacological, hormonal and nutritional states of the animal to determine if this enzyme contributes to the modulation of intracellular concentrations of long chain acyl coenzyme A thioesters. Mechanisms of regulation of the hydrolase(s) in vitro (viz. product of substrate inhibition, allosterism, etc.) will be investigated and attempts will be made to correlate these findings with the physiology of the animal and the secretory activity of the submaxillary gland to determine if the observed control mechanisms are operative in vivo.